Sorry for being a post hog today. :/
In re to the evidence and BARD, we have footage of a specific vehicle on location both immediately before and after the murders. That vehicle could belong to anyone who owns, borrows, or steals a white elantra. If no white elantra was reported stolen, that's a tentative check off. Now, that elantra didn't have a front plate, and if it didn't have a rear plate, or it was unknown if there was one, then that lack of plate info isn't helpful because anyone could remove the plates.
But, if that elantra did indeed have a rear plate, that narrows it down significantly when in a state that requires both plates. Being a college town, cars with only a rear plate is probably not uncommon, but that kind of situation would be highly indicative of a student, imo, because who would most likely be in a college town with out of state plates (a state that only requires a rear plate)? Process of elimination would come to play, I would imagine. Then when LE finds a match with WA plates on WSU campus, they look up and find out the WA plates were put on only 5 days after the murders, replacing PA plates, which only require rear. Boom.
Then you have cell phone data that parallels the car activity, at least before and after the murders, and conveniently turned off during the murders. You have cell phone data that put him close enough to "touch" one of the victim's wifi/bluetooth on previous occasion(s). The person who owns the elantra owns the phone. And the person who owns the elantra and phone also owns the DNA on a sheath discovered next to one of the bodies. And this is only the evidence we
know.
*To make a long story short, I believe he left the rear plate on, which ultimately helped pinpoint him specifically. JMO.